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Two New Species of Rhododendron (Ericaceae) from Guizhou, China

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Two New Species of Rhododendron (Ericaceae) from Guizhou, China Two New Species of Rhododendron (Ericaceae) from Guizhou, China Xiang Chen South China Botanical Garden, Chinese Academy of Sciences, 510650, Guangzhou, People’s Republic of China; Graduate School of Chinese Academy of Sciences, 100049, Beijing, People’s Republic of China; and Institute of Biology, Guizhou Academy of Sciences, 550009, Guiyang, People’s Republic of China. [email protected] Jia-Yong Huang Research Division, Management Committee for Baili Rhododendron Scenic Spot of Guizhou, 551500, Qianxi, People’s Republic of China Laurie Consaul Research Division, Botany, Canadian Museum of Nature, P.O. Box 3443, Station D, Ottawa, Ontario K1P 6P4, Canada. [email protected] Xun Chen Guizhou Academy of Sciences, 550001, Guiyang, People’s Republic of China. Author for correspondence: [email protected] ABSTRACT . Two new species, Rhododendron huang- 2005; Fang et al., 2005; Yang et al., 2006) and pingense Xiang Chen & Jia Y. Huang and R. lilacinum hundreds of similar herbarium specimens, we de- Xiang Chen & X. Chen (Ericaceae), from Guizhou scribe two previously undescribed species here. Province, China, are described and illustrated. Rhododendron huangpingense is close to the morpho- 1. Rhododendron huangpingense Xiang Chen & logically similar species R. oreodoxa Franch. var. Jia Y. Huang, sp. nov. TYPE: China. Guizhou: adenostylosum Fang & W. K. Hu and the sympatric Baili Rhododendron Nature Reserve, Pudi, species R. decorum Franch., from which it differs by 27u149N, 105u519E, 1719 m, 22 Apr. 2008, having short yellowish brown hairs on the leaves, the Xiang Chen 08024 (holotype, HGAS; isotype, rachis 15–18 mm long, a rose-colored corolla with MO). Figure 1. deep rose flecks, and the stigma ca. 3.5 mm wide. Rhododendron lilacinum differs from the morpholog- Haec species inter congeneros sympatricos Rhododendro ically similar and sympatric species R. simsii Planch. decoro Franch. simillima, sed ab eo foliorum indumento brevi by having smaller leaves, a shorter pedicel, a pale flavidobrunneo, inflorescentiae rhachide 15–18 mm longa, corolla rosea atroroseo-punctata atque stigmate ca. 3.5 mm purple corolla, a smaller calyx, and shorter stamens. lato distinguitur. Both of the new species appear to be quite rare and therefore their conservation is highly desired. Evergreen shrubs or small trees, 2.8–5.2 m tall; Key words: China, Ericaceae, Guizhou, IUCN bark grayish brown, exfoliating into thin and small Red List, Rhododendron. irregular flakes; branchlets glabrous. Petiole 1.4–2 cm, glabrous; leaf blade oblong or oblanceolate-elliptic, Baili Rhododendron Nature Reserve, a 125.8-km2 9–12(215) 3 2.7–4.5 cm, base cuneate or obtuse, highland located in northwest Guizhou Province, apex obtuse or rounded, apiculate, adaxial surface China, is characterized by a huge natural Rhododen- dark green, glabrous, abaxial surface pale yellowish dron L. population comprising approximately 35 green, sparsely puberulent, hairs denser along veins species of the genus. In the years 2007 and 2008, and yellowish brown; midrib slightly grooved adaxi- we conducted an intensive taxonomic survey of ally, prominent abaxially; lateral veins in ca. 16 to 18 Rhododendron in the area and, based on careful pairs, obscure adaxially, slightly raised abaxially. examination of the relevant literature (Ming, 1984; Inflorescences racemose-umbellate, 8- to 11-flowered; Fang & Ming, 1986; Hu, 1988; Zhang & Chen, 1990; bud scales deciduous; rachis 15–18 mm, sparsely Hu & Fang, 1994; Chen & Wu, 2003; Chen & Xie, glandular-puberulent; pedicels rose-colored, 1– NOVON 20: 386–391. PUBLISHED ON 29 NOVEMBER 2010. doi: 10.3417/2008102 Volume 20, Number 4 Chen et al. 387 2010 Rhododendron (Ericaceae) from China Figure 1. Rhododendron huangpingense Xiang Chen & Jia Y. Huang. —A. Flowering branch. —B. Androecium and gynoecium, with the corolla removed. —C. Detail of the leaf blade abaxial surface. Drawn by H. Xie from the holotype Xiang Chen 08024 (HGAS). 388 Novon Table 1. Taxonomic comparison of Rhododendron huangpingense Xiang Chen & Jia Y. Huang, R. oreodoxa Franch. var. adenostylosum Fang & W. K. Hu (Hu, 1988; Hu & Fang, 1994; Fang et al., 2005), and R. decorum Franch. (Hu & Fang, 1994; Fang et al., 2005). Characters R. huangpingense R. oreodoxa var. adenostylosum R. decorum Leaf blade abaxial surface pale yellowish green, pale green to whitish green, whitish green, glabrous color and vestiture sparsely puberulent with glabrous yellowish brown hairs Rachis length and vestiture 15–18 mm, sparsely ca. 5 mm, 20–25 mm, sparsely glandular glandular-puberulent glandular-tomentose Pedicel color and length rose, 1–1.5 cm purple, 0.5–1.5 cm slightly reddish green, 2.5–4 cm Corolla shape, color, and funnel-campanulate, campanulate, pale pink, funnel-campanulate, usually length rose, 4–5.5 cm 3.5–4.5 cm white, 3–5 cm Corolla scent and flecks not fragrant, with deep not fragrant, with or without fragrant, with no flecks rose flecks purple flecks Style length and stigma 3.8–4.2 cm, ca. 3.5 mm 2.8–3.4 cm, 1.6–2.6 mm 3.4–4 cm, ca. 5 mm width Capsule length 1.9–2.4 cm 1.8–3.2 mm 2.5–4 cm Geographic distribution NW Guizhou, 1679–1719 m W Sichuan, E Xizang, SW China, 1000–3000 m 3600–3900 m 1.5 cm, densely glandular-hairy. Calyx lobes 5 or 6, Phenology. The new species was observed in ca. 1.5 mm, broadly triangular or ovate, margin flower from April to May and in fruit from September sparsely glandular; corolla funnelform-campanulate, to November. rose-colored with deep rose flecks, 4–5.5 3 5.5–7 cm Discussion. Species of Rhododendron subg. Hy- when flattened, lobes 6 or 7, suborbicular, ca. 1.7 cm, menanthes (Blume) K. Koch sect. Ponticum G. Don emarginate, tube base sparsely glandular both outside subsect. Fortunea (Tagg) Sleumer are characterized by and inside, without nectar pouches; stamens 13 to 15, having glabrous branchlets, evergreen leaves without unequal, 2.5–3.5 cm, filaments densely puberulent scales, terminal inflorescences, a 6- or 7-lobed near base, anthers pale brown, ca. 2.5 mm; ovary corolla, 13 to 15 stamens, and a usually glandular conoid, 4–5.5 mm, densely yellowish glandular; style ovary and style. Therefore, it is reasonable to assign R. pale yellowish white, 3.8–4.2 cm, glandular-hairy to huangpingense to this subsection. This new species is the tip; stigma pale brown, ca. 3.5 mm wide. Capsule morphologically most similar to R. oreodoxa Franch. cylindric, slightly curved, 1.9–2.4 3 ca. 1 cm, with var. adenostylosum Fang & W. K. Hu, which belongs vestiges of glands. to the same subsection, but is an allopatric species Distribution, habitat, and IUCN Red List category. found in Sichuan and Xizang provinces in China. In Rhododendron huangpingense is restricted to slopes in Baili Rhododendron Nature Reserve, the new species the Baili Rhododendron Nature Reserve, Pudi, is most similar to the sympatric R. decorum Franch., Huangping County, Guizhou Province, China, where also of the same subsection. These three taxa differ by it grows in thickets dominated by R. delavayi Franch. the morphological characters listed in Table 1. and R. agastum Balf. f. & W. W. Sm. Since only two Paratype. CHINA. Guizhou: Baili Rhododendron Nature populations and a total of five mature individuals of Reserve, Pudi, Huangping, 27u139N, 105u519E, alt. 1679 m, this species were found in the area where the type slope, in thickets dominated by Rhododendron delavayi and R. collections were made, we make a preliminary agastum, 21 Apr. 2008, Xiang Chen 08018 (HGAS). conservation assessment for the species as Critically Endangered (CR), based on criterion D (population 2. Rhododendron lilacinum Xiang Chen & X. less than 50 mature individuals) of the IUCN Red List Chen, sp. nov. TYPE: China. Guizhou: Baili criteria (IUCN, 2001). Therefore, careful protection for Rhododendron Nature Reserve, Pudi, 27u139N, the species is warranted. The current major threats to 105u519E, 1674 m, 20 Apr. 2008, Xiang Chen the species are human disturbance or damage 08008 (holotype, HGAS; isotype, MO). Figure 2. (recreation/tourism), since its locality is a scenic spot in a rural mountain setting, and habitat loss (agricul- Haec species Rhododendro simsii Planch. similis, sed ab ture), despite the fact that the region is a provincial ea foliis minoribus, pedicello breviore, corolla pallide nature reserve. Fortunately, a few seedlings were found purpurea atque calyce staminibusque brevioribus distingui- tur. under the mature individuals, and one of the authors, Huang Jia-Yong, has collected seeds and begun a Shrubs, deciduous, ca. 2 m tall; branchlets thin, propagation experiment. densely dark brown strigose. Petioles 3–6 mm, Volume 20, Number 4 Chen et al. 389 2010 Rhododendron (Ericaceae) from China Figure 2. Rhododendron lilacinum Xiang Chen & X. Chen. —A. Flowering branch. —B. Androecium and gynoecium, with the corolla removed. —C. Enlargement of leaf blade abaxial surface. —D. Detail of filament base. Drawn by H. Xie from the holotype Xiang Chen 08008 (HGAS). densely dark brown strigose; leaf blade papery, along midrib and on abaxial surfaces; midrib somewhat thick, elliptic, 1.5–2.3 3 0.7–1 cm, margin conspicuous on both surfaces; lateral veins in 5 to 8 entire, base cuneate or obtuse, apex acute, both pairs, obscure adaxially, slightly raised abaxially. surfaces coarsely pale brown strigose, hairs denser Inflorescence terminal, umbellate, 2- or 3-flowered; 390 Novon Table 2. Taxonomic comparison between Rhododendron lilacinum Xiang Chen & X. Chen and R. simsii Planch. (Hu & Fang, 1994; Fang et al., 2005). Characters R. lilacinum R. simsii Leaf blade shape, dimensions, and elliptic, 1.5–2.3 3 0.7–1 cm, margin ovate, elliptic-ovate, 1.5–5 3 0.5–3 cm, margin entire margin finely toothed Pedicel length 2.5–3 mm 8 mm Calyx length ca. 1 mm ca. 5 mm Corolla shape and length funnelform, ca.
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